The present invention relates to systems for epilation or the permanent removal of hair from subcutaneous tissue (tissue at and below the skin), and particularly to an improved system (method and apparatus) for epilation utilizing laser beam energy.
This application is related to an earlier, commonly owned, application, U.S. Ser. No. 08/094,296 filed Jul. 21, 1993 pending and entitled, Dermatological Laser Treatment System With Electronic Visualization of the Area Being Treated. The present invention provides a treatment system wherein the treatment is epilation and the laser energy is shaped into a beam which matches the geometry of the hair root (the hair and the hair follicle including the bulb and dermal papilla at the base thereof). This beam is of sufficient fluence at the selected wavelength to progressively ablate or vaporize the hair root, but because of its shape and the divergence at depth below the hair root, only the hair root is treated. The beam may be shaped to have its narrowest cross-section or waist at the skin's surface and a divergence which decreases the optical energy density outside of an ablation cavity which includes essentially only the hair root.
Optical beams for hair removal have been suggested in several patents which are discussed below. The optical energy is not used to ablate the hair and its root structure as provided for by the present invention, in that beam delivery system is not an optical system which shapes and restricts the beam to a subcutaneous ablation cavity, that is a volume where ablation can occur and is restricted.
In U.S. Pat. No. 5,059,192, issued to Zaias on Oct. 22, 1991 and in Weissman, et al., U.S. Pat. No. 4,388,924 issued Jun. 21, 1983 and in a patent issued Jul. 13, 1993 to Tankovich, U.S. Pat. No. 5,226,907, reliance is placed on selective photothermolysis, that is the selective absorption of the incident laser radiation by the melanin in the follicle to cause localized heating.
Sutton, in U.S. Pat. No. 4,617,926 issued Oct. 21, 1986, alleges that the hair can be used as a optical waveguide to conduct the optical energy to the base of the follicle without damaging the surrounding tissues. No explanation is given as to how hair, which is not transparent nor hollow, can function as a waveguide, so that the operability of the Sutton proposal is questionable. Other proposals have involved probes which must be inserted much like electrolysis needles to deliver the optical energy directly to the hair root. See Block U.S. Pat. No. 3,834,391 issued Sep. 10, 1974 and Mayer, U.S. Pat. No. 3,538,919 issued Nov. 10, 1970.
The delivery of the energy may be through the use of a hand piece having means for scanning a beam in order to locate the entrance to the hair root structure at the skin. Other automatic and semiautomatic systems for locating a housing carrying the laser beam and its optical system may be used. The U.S. patent to Weissman referenced above shows one such system. Another system is described in French Patent Application 2,590,791 published Jun. 5, 1987.
Accordingly, it is the principal object of the present invention to provide an improved epilation system for permanent removal of hair which relies upon geometric shaping of a laser beam so as to ablate only the hair and the root structure and vascular system which supports the growth of the hair, without reliance on selective photothermolysis, but rather on the geometry of the beam in order to limit the tissue which is surgically removed thereby reducing damage to surrounding tissue.
It is a still further object of the present invention to provide an improved epilation system using optical means for beam shaping and relying upon the spatial characteristics of the beam (Gaussian/Truncated) and the divergence of the beam due diffraction effects in order to adjust the geometry of the beam and to confine it to an ablation cavity containing and limited to the root structure to be excised by the laser beam.
Briefly described, the invention utilizes means for directing a laser beam of sufficient fluence at the selected wave length to vaporize a hair and its root structure which surrounds and supports the growth of the hair in the epidermis, dermis and subcutaneous tissue of the skin. The beam is directed in a manner to optically confine it to the root structure within an ablation cavity, spatially matching the root structure. Laser energy is, thereby, delivered from the beam to expose the hair and the root structure progressively inwardly of the skin's surface until the root structure and any hair therein is ablated without substantial damage to tissue surrounding the root structure.